Vibrio anguillarum is popular pathogenic bacteria of aquaculture animals around the world and can infect salmon, steelhead, eel, plecoglossus altivelis, weever, gadidae, turbot, flounder, yellow croaker and the like (Gao Dongmei, Li ham and Wang Qun, Study on immune efficacy induced by killed Vibrio anguillarum vaccine on Flounder, Marine Fisheries Research, 2004, 25(1): 486-492). As for part of fish infected with the Vibrio anguillarum, local color fading appeared on the body surfaces firstly, fin rays, fin bases and the lower parts of branchial skeletons were engorged and redden, the anus were red and swollen, then the muscle tissues had disseminated or point-like hemorrhage, the body surfaces became black and the fins had ulceration; and when dissection test was performed, obvious yellow viscous ascites was observed, intestinal mucosa tissues became rotten and fell off, and the livers of part of the fish were necrotized (Xiao Hui, Li Jun, Xu Huaishu, et al., Studies on Pathogens of Rotted Gill and Rotted Caudal Fins of Seaperch, Journal of Ocean University of Qingdao, 1999, 29(1):89). The Vibrio anguillarum is a serious disease in aquaculture.
Cyclic peptide type compounds, namely Cyclo(D)-Pro-(D)-Ile (compound 2), Cyclo(D)-Pro-(D)-Leu (compound 3) and Cyclo(D)-trans-4-OH-Pro-(D)-Phe (compound 4) are known compounds, the structural formulae are as shown in Formula (II) and the compounds were disclosed in the following documents: document 1, Journal of Natural Products, 2003, 66(10): 1299-1301; document 2, Journal of Natural Products, 1995, 58 (2): 201-208; and document 3, Anal Bioanal Chem, 2010, 396:1773-1779. The Cyclo(D)-Pro-(D)-Ile (compound 2), the Cyclo(D)-Pro-(D)-Leu (compound 3) and the Cyclo(D)-trans-4-OH-Pro-(D)-Phe (compound 4) disclosed in Fdhila F et al., Journal of Natural Products, 2003, 66(10): 1299-1301 had great bactericidal activity against the Vibrio anguillarum.
